Vine Buds: How They Affect Wine Quantity and Quality

To the casual observer, grape vines seem to suddenly sprout up in the spring, produce grape clusters in the fall, and go dormant in the winter. While this is broadly true, the actual growth cycle of a vine is a continuum that endures each and every day for life. In particular, the business of vine buds is often overlooked, but it is as important to grape vines as caterpillars are to butterflies.

Bud basics
A grape vine may simultaneously possess buds from multiple growing seasons, but in general, only those that formed on shoots during the previous spring have a chance to be fruitful. In other words, the buds that will produce shoots, leaves and clusters next year developed on infant shoots early this spring. “This phenomenon is significant,” says Winemaker George Troquato, “because the size of next year’s crop is partly determined by the viability of the buds existing on the current growth as well as the temperature, sunlight and moisture affecting them.” Flowering, fruit set, berry growth, disease and pruning also determine yield.

A bud is not just a bud
A bud is a compound entity containing three tiny buds (primary, secondary and tertiary) that hold the potential for becoming shoots bearing leaves, clusters (two per shoot on average) and tendrils (unfruitful clusters). “The primary buds are the default, but a vine will use the secondary ones if the primaries are damaged by frost or eaten by wildlife,” says George.

While Mother Nature dictates bud performance for the most part, winegrowers have a chance to enhance vine efficiency because pruning regulates bud production. Pruning techniques vary according to region and climate, but they should always be carried out to achieve maximum vine balance with several growing seasons in mind. (See our story on “Vine Balance and Yield” to learn more about the effects of pruning on wine quantity and quality.)

In conclusion
“Managing vines is a skilled practice,” says George, “and the culmination of a million tasks. Vines have tremendous ‘memory’, so decisions — right or wrong — persist for years in the vine and have long-lasting effects.”

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